It is known to provide a roof mounted air deflector panel which is hingedly mounted for pivotal movement relative to the cab roof.
One such aerodynamic drag reducer is disclosed in Taylor et al. U.S. Pat. No. Taylor et al. 4,165,543 assigned to the assignee of this invention. The aerodynamic drag reducing efficiency of the pivotal deflector panel is enhanced by the use of adjustable bellows type side members of flexible material which extends between the cab roof and the deflector panel. The side members are preferably molded of a semi-rigid urethane and include a plurality of foldably interconnected segments of a triangular shape which fold and unfold relative to one another to accommodate variation in the angle of the deflector panel relative to the cab roof.
It is characteristic of such side members that the flexibility thereof required to enable folding and unfolding during pivotal movement of the deflector panel also permits the side members to be bowed inwardly or outwardly by air pressure or to flap back and forth in the air stream. Furthermore the flexible material may be difficult to control during collapse of the deflector panel to the stored position on the cab roof so that the folded segments may bunch inwardly or outwardly instead of folding and stacking neatly on top of each other.
Accordingly it would be desirable to provide a guide arrangement which would support the side member segments relative one another when the deflector panel is raised and would function to guide the segments for stacking storage one atop another when the deflector panel is collapsed to the stored position upon the cab roof.